The rapid development of optoelectronics has produced a desire for methods of producing nanometer-sized patterns on semiconductor surfaces. Typically, these patterns can be etched into semiconductor substrates by a number of techniques. For example, wet chemical etching has been used to etch a wide variety of semiconductors. Typically, for the case of II-VI semiconductors such as ZnSe, wet chemical etching utilizes bromine-based chemistries. Wet chemical etching proceeds by oxidation of the semiconductor constituents followed by chemical dissolution of the oxides in suitable solvents.
Currently Br2—HBr based etching solutions can be used for producing smooth, defect-free surfaces or for patterning II-VI semiconductors. This bromine-based etchant works very well for II-VI semiconductors such as those, for example, that can be used for the fabrication of down-converters to modify the wavelengths of laser diodes or light emitting diodes (LEDs). A big drawback in using bromine-based etchant solutions is that they exhibit storage instability. The instability is due to evaporation of bromine as well as side reactions in which bromine is consumed. Furthermore, since the etching rate is proportional to the concentration of bromine, the control of etch depth can be poor in the absence of an etch stopper.